Yeah, not a fan either.
I'd prefer for the trader inventory to be mostly "virtualized", with only a limited amount of money and a couple of hand-placed small items being available for pick pocketing.
And YEAH, I expect it to be an absolutely UNPOPULAR opinion, too.
My Wood Elf Warlock is pretty much an exceptional pickpocket. Mediocre to bad at nearly everything but thief skills and casting friends on himself.
You can absolutely cheese getting a ton of items this way, but I'm of two minds about it. I think the store owners should have their gold purse on them, and maybe some personal items that aren't for sale.
So you're stealing money but you wind up having to pay them back to buy anything really good.
I also think there should be auto successes for pickpocketing, but that the difficulty gets higher the more times you try to pilfer from a single target in a row.
Something where it starts off rather easy and gives some validation to rogues and rogue-like characters, but gets harder the more chances you take so you can't abuse it too much without save scumming.